☁️BizyAir Realistic Lineart

Lineart is the softer, more forgiving cousin of a Canny edge extraction, and it's the standard pick when you want a ControlNet condition that preserves an image's structure without dictating every pixel-hard edge. This node runs the "realistic lineart" extractor from the standard controlnet-preprocessor lineup, over BizyAir's cloud instead of a local model, so there's nothing to download to your models/ folder.

Realistic vs. coarse, and why it matters

There isn't a huge menu of options here on purpose, this preprocessor does one job. coarse is the only thing that changes the character of the output: disabled (the default) gives you thinner, more natural realistic lines that track actual contours in the image. Enabled, it switches to bold, sketch-like strokes, more suited to a stylized or illustration-leaning generation than a photoreal one. If your generations are coming out looking like a technical sketch when you wanted something closer to the source photo, that's almost certainly coarse set to enable when you wanted it off, and vice versa if you wanted bolder strokes and got thin realistic lines instead.

resolution is the usual preprocessing-size tradeoff, 512 by default, worth bumping toward 1024 if your final generation is large and you need the line map to hold detail at that scale.

Lineart's real strength shows up when it's paired with Reference conditioning to keep a character's proportions and silhouette consistent while changing everything else about a scene, though that pairing is more of an SD 1.5/SDXL-era trick since Reference-style conditioning hasn't been rebuilt for the newer flow-matching architectures. On any base, lineart alone is a solid choice any time you want the model to keep an image's structure while having real freedom over shading, color and fine texture, which is why it's often preferred over Canny for organic subjects like people and animals.

Wiring it up

Output is a single IMAGE, the line map, feed that into whatever lineart or general-purpose ControlNet loader your base model has a checkpoint for. Weight and step-range guidance follows the same pattern as any structural ControlNet condition: start lower (0.5-0.8) if you want the model to still have room to invent shading and detail, push higher if the line structure needs to hold exactly, and ending ControlNet influence partway through the sampling steps rather than running it the whole way through tends to give cleaner, less "traced" results.

Installing it

Through ComfyUI Manager, search "BizyAir" and install, then restart. Or clone it directly:

cd ComfyUI/custom_nodes && git clone https://github.com/siliconflow/BizyAir.git

You'll need a BizyAir/SiliconFlow API key set up before this preprocessor will actually run, the README points you to a "click to login" prompt the first time you use any BizyAir node. Signup runs through phone-number verification, and it's worth knowing in advance that some users outside China have hit friction there.

Common issues

If the node doesn't execute and there's no obvious workflow error, the API key is the first thing to check, that accounts for the large majority of BizyAir failures generally, not anything specific to this preprocessor. If the extracted lines look wrong for what you wanted, double-check coarse before touching anything else, it's a single toggle and the most common source of "this looks nothing like what I expected" reports for lineart nodes generally.

Worth knowing separately: ComfyUI Manager sometimes auto-installs the whole BizyAir pack when it misresolves a missing-node error on an older shared workflow, particularly ones built before Manager's node registry improved in early 2025. That's confusing but not malicious, it's real software from SiliconFlow, and you can remove it through the Manager if you didn't ask for it.